These studies deal with influences of age on the biochemistry of hormone-sensitive adenylate cyclases in a variety of tissues. The purpose of these studies is to explore the mechanisms of age-related alterations of hormone responsiveness and biological membranes. The work utilizes preparations of materials from rats and human (liver, fat). BIBLIOGRAPHIC REFERENCES: Cooper, B., Partilla, J.S., and Gregerman, R.I.: Enhanced Activity of Hormone-Sensitive Adenylate Cyclase during Dietary Restriction in the Rat. Dependence on Age and Relation to Cell Size. Journal of Clinical Investigation 59: 467-474, 1977.